(19)

(11)

EP 0 666 893 A1

(12)

(43) Date of publication: 16.08.1995 Bulletin 1995/33 (21) Application number: 94924941.0 (22) Date of filing: 30.08.1994

(51) International Patent Classification (IPC):  C09K 8/ 34( . ) (86) International application number: PCT/GB1994/001878 (87) International publication number: WO 1995/006695 (09.03.1995 Gazette 1995/11)

(84) Designated Contracting States: AT BE DE DK ES FR GB IT NL (30) Priority: 01.09.1993 GB 19930018100 29.06.1994 GB 19940013075 (71) Applicants: SOFITECH N.V. Uccle (1180 Bruxelles) (BE) COMPAGNIE DES SERVICES DOWELL SCHLUMBERGER S.A. F-92541 Montrouge (FR)	(72) Inventor: SAWDON, Christopher, Alan Par Cornwall PL24 2HJ (GB) (74) Representative: Nash, David Allan, et al  Haseltine Lake & Co. 28 Southampton Buildings Chancery Lane London WC2A 1AT London WC2A 1AT (GB)